Personality can be defined in terms of enduring individual differences in emotional, interpersonal, experiential, and motivational styles. The five factors of Neuroticism, Extraversion, Openness to Experience, Agreeableness, and Conscientiousness provide a comprehensive taxonomy of personality traits for the description of personality in aging men and women. As part of an ongoing series of studies on these basic dimensions, section investigators refined measures of facets of Agreeableness and Conscientiousness and demonstrated invariance of the five-factor structure across age, race, and gender groups. In another project, an index of profile agreement was developed to quantify the degree of similarity of personality profiles obtained from different observers' reports; in empirical comparisons, this index was shown to be superior to alternative indices in discriminating matched from mismatched profiles.